Quasiparticle band structure, exciton, and optical properties of few-layer blue phosphorus

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The evolution of quasiparticle electronic structure, exciton, and optical properties in the few-layer blue phosphorus has been studied with the many-body perturbation method. The quasiparticle band gap decreases gradually with increasing the layer number and the system will finally evolve to metallic state in the bulk form. In spite of the increasing thickness in these indirect-band-gap semiconductors, the exciton-dominated optical properties with large binding energies are still found in the few-layer systems. With increasing layer number, the overall dielectric screening gets enhanced. However, the persistent large joint density of states associated with the parallel band structure in blue phosphorus gives rise to a much larger binding energy than the value predicted in an effective screening model. Our studies have not only provided a deep understanding of excitons in 2D semiconductors but also provided solid data for further experimental exploration of the application of few-layer blue phosphorus in optoelectronics.